Reply:
======

* M. Petruzzellis
* R. De Blasi
* V. Lucivero
* M. Sancilio
* M. Prontera
* A. Tinelli
* D.M. Mezzapesa
* F. Federico

We thank Dr. Fox for his comments concerning our previously published letter to the editor entitled, “Cerebral Aneurysms in a Patient with Osteogenesis Imperfecta and Exon 28 Polymorphism Of *COL1A2*.”1 He strongly informs us of a misunderstanding regarding the de novo aneurysm that developed after 4 months. Dr. Fox points out some potential errors in our diagnosis, claiming that the de novo aneurysm is actually a refilling of the previously treated one. We believe that indeed at 4 months, our images revealed that a new aneurysm had developed in front of the previous one (Fig 2*B*). Further evidence of this was found in the posttreatment un-subtracted images (not published due to space constraints), in which it was possible to appreciate the stent crossing the vertebrobasilar junction and the coils occluding 2 different and clearly separable aneurysms.

Finally, we are grateful to Dr. Fox for bringing to our attention some bibliographic references that may help us achieve a better understanding of the anatomic features of this particular case.

## Reference

1.  Petruzzellis M, De Blasi R, Lucivero V, et al. **Cerebral aneurysms in a patient with osteogenesis imperfecta and exon 28 polymorphism of *COL1A2*.** AJNR Am J Neuroradiol 2007;28:397–98
    
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